Segmented radial or circumferential seals have been employed in a number of environments associated with compressible fluids, such as gases. They have been used, for example, in connection with gas turbine engines. Such radial seals typically act to, among other things, seal high pressure areas from low pressure areas.
Conventional segmented seals commonly utilize a shallow face groove to control axial loading on the segmented seal. However, the radial position of the shallow face groove is limited due to the run-out of the shaft and the ability of the secondary seal to maintain contact with the sealing surface of the housing. Axial loading of segments is commonly required to maintain an adequate secondary seal contact between the secondary surface of the segment and a mating sealing surface. As axial loading on the segment increases, the ability of the segment to track shaft run out or respond to transient excursions of the shaft is negatively affected. In a number of applications the shallow face groove seal is positioned as low radially as possible to minimize pressure effects, therefore minimizing the axial loading on the segments but decreasing the secondary seal surface area.
Among other things, it is desirable to provide a segmented seal in which the radial location that the system pressure can act on, and can even be adjusted, to reduce the axial loading that the system pressure may apply to the segment without compromising the secondary seal surface area.